Patent GB-378627-A (GB)
Title: Improvements in and relating to apparatus for withdrawing single sheets from a stackof sheets
IPC: B65H3/10
Filed: 1931-07-24
Abstract: 378,627. Feeding sheets. WINKLER, A. and DUNNEBIER, M., Neuwied, Germany. July 24, 1931, No. 21207. [Class 100 (i).] Sheet separators and carriers ; pile supports.- Sheets are separated from a stack 1, Fig. 1, resting on an inclined or other support 2 by means of a pair of oppositely rotating rollers 7, 8, of which the roller 7 is of hollow construction and carries on its periphery sheet-separating means acting either by suction, or friction, or in the form of sheet-engaging needles, for gripping the sheet at one of its edges. The roller 7 is provided with an opening which is arranged behind the sheet-engaging means, and the edge of the sheet is first bulged out by the sheetengaging means and is guided into the opening in the roller 7, and subsequently the edge 13<1> of the roller 7 engages the partly separated sheet and causes it to be gripped between the two rollers 7, 8, which withdraw the sheet from the stack either completely or, if the sheets are to be advanced in overlapped condition, partly only, the roller 8 being formed in this case with an active raised sector 22 of a length equal to the desired amount of overlap of the sheets. The pile is controlled by adjustable side stops 4, and the sheet-engaging device is shown as consisting of suction orifices 12 leading from a passage 11 in which a vacuum is produced intermittently. The top edge K of the pile is supported by supports 5 which are either fixed, or are oscillated by a cam on the roller 7 to release the bottom sheet, and then to return to the pile to prevent the separated sheet from returning into contact with the pile. A groove in the roller 7 permits the stack to drop to the level of the roller 7, but the supports 5, when moved inwards, raise the pile above the level of the roller 7. In the position shown in Fig. 1 suction is applied to the openings 12, and the front edge of the bottom sheet is carried round thereby and the sheet is bulged out until it nearly fills the space between the rollers 7, 8. The suction is then cut off, and the sheet passes into an opening 13 in the roller 7, and the edge 13<1> of this opening engages the sheet and forces it between the rollers 7, 8 which effect the separation as stated. If the sheets are to be separated completely, the roller 8 is constructed as a complete roller. The sheets are advanced by a positively driven roller 23 and a spring-pressed roller 24 which is set to advance the sheets only when they are being propelled also by the rollers 7, 8. In a modification, Fig. 3, the sheet is separated by a bar 27 of rubber, and the bulged-out sheet is prevented from returning to the stack by cam-actuated sliding sheet holders 28 which are projected into the bulge from either side of the stack. In a further modification, Figs..5 and 9, suction sheet-engaging members 40 are carried by a flap 38 pivoted to the roller 7, and the flap is oscillated by cam mechanism to withdraw into the roller 7, as shown in Fig. 5, by dotted lines, after the sheet is engaged. The suction chamber 40 is connected to a hollow tube 45 about which the flap 38 pivots, and the air pressure in the chamber 40 is controlled by means of a rotating disc 46 formed with a radial slit 47 which also tapers in the direction of a fixed disc 48, which is formed with a segmental recess 50 connected by a tubular connection 51 to a rotary air pump. The suction effect commences when the slit 47 registers with the recess 50, and ends when the slit passes the recess. The disc 48 can be set in different positions to vary the time at which the suction effect commences. In further modifications a pivoted flap 38 can be fitted with a rubber friction pad ; or a suction flap may be pivoted about an axis arranged behind the suction chamber 40 ; or a pivoted flap may be fitted with needles which engage the sheet, and the needles are arranged to be withdrawn from the sheet as the flap moves inwards. The roller 7 can be arranged at the lower end of the stack 1, and the support 2 is then bent downwards as shown in Fig. 16. The suction separating member in this case is formed as a hollow roller 72 carried by pivoted flap members 76 which are oscillated by cam mechanism. Alternatively the roller 72 may be rotatably mounted in the roller 7. In either case the roller 72 is rotated by a pinion engaging a rack, and the sheet is carried into the roller 7 bv the rotation of the roller 72. To assist the separation of the sheets the roller 7 is driven at a variable speed by means of elliptical gearing which accelerates the roller 7 after partial separation of the sheet by the roller 72. A further suction separator acting on the top edge of the sheet is also provided consisting of a segmental suction roller 92 carried by a pair of oscillating levers 95, and the roller 92 is rotated clockwise by a rack and pinion as it moves to the left. The edge of the sheet is wrapped round the roller 92, and a swinging stack support 105 fitted with a coating 106 of roughened rubber moves in to engage the pile to prevent a second sheet from being fed and to assist in the separation of the edge of the next sheet. In further modifications, the stack may be arranged to be horizontal and the sheets fed from the bottom or the top of the stack ; also two or more sheet-engaging members may be arranged on one roller 7. The roller 8 may be of smaller size than the roller 7, and in this case the roller 8 may contact intermittently with the roller 7 either by being mounted in lever arms which are oscillated so as to bring the roller 8 into and out of contact with the roller 7, or the roller 8 may be constructed with enlarged ends which contact with the roller 7 and with a central grooved or lower portion which is of greater width than the sheet, and provided with a pivoted flap which can be moved outwards so as to cause its curved outer surface to coact with the roller 7 when it is desired to grip a sheet and forward it by the combined action of the pivoted flap and the surface of the roller 7. The roller 7 may be formed as the impression cylinder of a perfecting printing-couple, and the separated sheets after receiving their first impression are transferred from the cylinder 7 to the second impression cylinder of the couple. The withdrawal of the bottom sheet of an inclined stack may be assisted by means of a blast of air which is directed between the plate 2 and the bottom of the pile.